Biotechnology

• The biotechnology industry is pretty big these days
• Biotechnology


  The industrial use of living organisms (or parts of living organisms) to produce food, drugs and other products
• Living organisms used in biotechnology

  • Microorganisms (bacteria and fungi)
• Reasons why microorganisms are used in biotechnology

  • Their ideal growth conditions can be easily created
  • They grow rapidly under the right conditions
  • They can grow on a range of inexpensive materials
  • They can be grown at any time of the year
• Intracellular enzymes


  Enzymes contained within the cells of microorganisms
• Isolated enzymes


  Enzymes not contained within cells
• Extracellular enzymes


  Enzymes that are secreted naturally by microorganisms
• Enzymes used in biotechnology

  • Lactase (the enzyme that breaks down lactose)
• Brewing (making beer)


  1. Yeast (eg. Saccharomyces cerevisiae) is added to grain and other ingredients

  2. Yeast respires anaerobically using the glucose from the grain and produces ethanol (alcohol) and CO2
• Baking


  Yeast makes bread rise by producing CO2 through fermentation of sugars in the dough
• Cheese making


  1. Rennet containing the enzyme chymosin clots the milk

  2. Lactic acid bacteria (e.g. Lactobacillus and Streptococcus) convert lactose into lactic acid, causing the milk to turn sour and solidify

  3. Fungi are added to make blue cheeses
• Yoghurt production


  Lactic acid bacteria are used to clot the milk and cause it to thicken
• Penicillin production


  Fungi from the Penicillium genus are grown under stress in industrial fermenters to produce penicillin
• Insulin production


  Genetically modified bacteria with the human insulin gene are grown in an industrial fermenter to produce insulin
• Bioremediation


  Pollutant-removing bacteria are provided with extra nutrients and enhanced growing conditions to allow them to multiply and break down pollutants
• Example of bioremediation


  • After an oil spill near Valdez, Alaska, microorganisms present in the area were able to biodegrade the oil when provided with additional nutrients
• Advantages of using microorganisms to produce food

  • Microorganisms can be grown using many different organic substrates, including waste materials
  • Production costs are low because microorganisms have simple growth requirements
  • Microorganisms can be cultured anywhere with the right equipment
  • Single-cell protein is often considered a healthier alternative to animal protein
• Disadvantages of using microorganisms to produce food

  • Lots of effort is required to prevent contamination
  • People may not like the idea of eating food grown using waste products
  • Single-cell protein doesn't have the same texture or flavour as real meat
  • High consumption of single-cell protein could cause health problems
• Batch fermentation


  Microorganisms are grown in individual batches in a fermentation vessel
• Continuous fermentation


  Microorganisms are continually grown in a fermentation vessel with nutrients added and waste products removed at a constant rate
• Factors controlled in a fermentation vessel

  • pH
  • Temperature
  • Oxygen supply
  • Nutrient concentration
• The conditions inside the fermentation vessels are kept at the optimum for growth to maximise the yield of microorganisms and desirable products
• Growth curve of a cloned culture

  Standard growth curve with lag, exponential, stationary and death phases
• Factors that need to be controlled in a fermentation vessel

  • pH
  • Temperature
  • Oxygen supply
  • Nutrient concentration
  • Contamination
• pH control in a fermentation vessel

  1. pH is monitored by a pH probe

  2. pH is kept at the optimum level
• Keeping pH at optimum level

  Increases product yield because enzymes can work efficiently, so the rate of reaction is kept as high as possible
• Temperature control in a fermentation vessel

  Temperature is kept at the optimum level by a water jacket that surrounds the vessel
• Keeping temperature at optimum level

  Increases product yield because enzymes can work efficiently, so the rate of reaction is kept as high as possible
• Oxygen supply control in a fermentation vessel

  The volume of oxygen is kept at the optimum level for respiration by pumping in sterile air when needed
• Maintaining optimum oxygen supply


  Increases product yield because microorganisms can always respire to provide the energy for growth
• Nutrient concentration control in a fermentation vessel

  Microorganisms are kept in contact with fresh medium by paddles that circulate the medium around the vessel
• Maintaining optimum nutrient concentration

  Increases product yield because microorganisms can always access the nutrients needed for growth
• Contamination control in a fermentation vessel


  Vessels are sterilised between uses with superheated steam to kill any unwanted organisms and make sure the next culture is not contaminated
• Preventing contamination


  Increases product yield because the microorganisms aren't competing with other organisms
• Closed culture


  Growth takes place in a vessel that's isolated from the external environment during growth, so nothing is added and waste products aren't removed
• Growth curve of microorganisms in a closed culture

  • Lag phase
  • Exponential (log) phase
  • Stationary phase
  • Decline phase
• Lag phase


  Population size increases very slowly because the microorganisms have to make enzymes and other molecules before they can reproduce, so the reproduction rate is low
• Exponential (log) phase


  Population size increases quickly because the culture conditions are at their most favourable for reproduction (lots of food and little competition), so the number of microorganisms doubles at regular intervals
• Stationary phase


  Population size stays level because the death rate of the microorganisms equals their reproductive rate, as food becomes scarce and waste products build up
• Decline phase


  Population size falls because the death rate is greater than the reproductive rate, as food is very scarce and waste products are at toxic levels